Prior to the present invention various fastening units and procedures have been devised and employed in metal fabrication to improve connection of components to one another. For example blind fasteners and resistance spot welds have been utilized for joining discrete sheets of aluminum and alloys thereof so that lightweight assemblies can be manufactured. Such connections were often instituted for significant weight reduction in a wide range of applications, for example in automotive vehicles where weight reduction translates into increased operating fuel economy.
Adhesives have also been incorporated into mechanical fastener units to improve connections in other applications. In US patents to Krug et al: U.S. Pat. No. 5,375,953 issued Dec. 27, 1994 for Blind Rivet and U.S. Pat. No. 5,473,806 issued Dec. 12, 1995 for Method of Preventing Cold Welding Especially of Blind Rivets, laterally spaced retention grooves are provided in the mandrels of blind fasteners to carry curable adhesives that cooperates with the mechanical connecting aspects of the rivet to effect an optimized fastening of multiple components. In US patent to Newton U.S. Pat. No. 3,772,957 issued Nov. 20, 1973 for Self Drilling and Sealing Rivet, discrete chambers are specially formed between a self-drilling mandrel and the cylindrical body of the rivet to separate resin and hardener components of an epoxy for subsequent intermixing and curing to augment mechanical fastening. In U.S patent to Del Mundo et al U.S. Pat. No. 4,659,268 issued Apr. 21, 1987 for Composite Blind Fastener, concentric annular receptacles are provided in the end of a blind rivet for the discrete epoxy components which are intermixed when the rivet is set to effect a combination mechanical and adhesive connection between a pair of plates.
While these prior constructions and methods are appropriate to meet their objectives, they generally are difficult to produce and have exposed adhesives or various mandrel modifications to separate the resin and hardener portions of the epoxy. Accordingly they do not meet new and higher standards for the economical and sealed packaging of the adhesive within the blind fastener nor the new and improved blind fastener connection augmented by the adhesive connection provided by a predetermined sealed charge of adhesive. More particularly, the prior art does not disclose or suggest the new and improved methods of charging a blind fastener unit with an adhesive such as provided in the present invention.